Burner assembly

ABSTRACT

A burner assembly for a gas-fired furnace including a heat exchanger mounted in a housing in heat transfer relation with flowing air passing over the heat transfer surface of the heat exchanger, the gas burner assembly including a chamber of serrated cross-section, each serrated cross-section being a generally V-shaped pocket therein whereby fuel enters the chamber parallel to the axis of the chamber and each V-shaped pocket includes two flanks, a first flank having at least one aperture therein for combustion air to enter the chamber tranversely of the fuel passing through each V-shaped pocket, and a second flank having a baffle attached thereto whereby the fuel gas and the air mixing in the pockets are directed tangentially toward the center of the chamber.

United States Patent [191 Mutchler [54] BURNER ASSEMBLY [75] Inventor:Paul A. Mutchler, University City,

[73] Assignee: American Air Filter Company, Inc.,

Louisville, Ky.

[22] Filed: July 10, 1972 [21] Appl. N0.: 270,157

2,018,582 10/1935 Theunissen....

[4 1 Apr. 17, 1973 Primary Examiner-William E. Wayner AssistantExaminer-William E. Tapolcai, Jr. Attorney-Ralph B. Brick et al.

[57] ABSTRACT A burner assembly for a gas-fired furnace including a heatexchanger mounted in a housing in heat transfer relation with flowingair passing over the heat transfer surface of the heat exchanger, thegas burner assembly including a chamber of serrated cross-section, eachserrated cross-section being a generally V-shaped pocket therein wherebyfuel enters the chamber parallel to the axis of the chamber and eachV-shaped pocket includes two flanks, a first flank having at least oneaperture therein for combustion air to enter the chamber tranversely ofthe fuel passing through each V-shaped pocket, and a second flank havinga baffle attached thereto whereby the fuel gas and the air mixing in thepockets are directed tangentially toward the center of the chamber.

2 Claims, 6 Drawing Figures PATENTED APR 1 71973 SHEET 1 BF 3 PATENTEDAPR 1 "(I973 SHEEI 2 [IF 3 PATENTEDAPR 1 11915 3'. 728,07 1

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BURNER ASSEMBLY BACKGROUND OF THE INVENTION This invention relates to aburner assembly for a gasfired furnace and more particularly, to a novelgas burner assembly including flame directing baffles therein, the gasburner assembly being adaptable for cooperating with a heat exchanger.

In previous forced draft burner constructions for gasfired furnaceshaving horizontal return tubes, high velocity nozzles from smalldiameter burner blast tubes have been used to fire into rectangularrefractory combustion chambers 01', unnecessarily large cylindricalfurnace tubes. In accordance with the present invention it is recognizedthat these high velocity flows often have a tendency to cause momentaryblowoff of the flame at the burner blast tube end and the gas fires thatare late in developing their maximum heat release have tended to makelittle use of the direct heating surface near the burner or firing endof the furnace. The present invention further recognizes that these latedeveloping gas fires also have led to overworking and overheating of therear tube sheet which causes for short life and early failure of therear tube sheet and the horizontal return tube end where the tubes jointhe rear tube sheet. Moreover, it is recognized that full advantage hasnot been made of the primary heating surface of the furnace therebymaking it necessary to operate a gas burner with minimum excess air inorder to keep the stack temperature down to a level necessary to achievethe required furnace efficiency.

SUMMARY OF THE INVENTION The present invention, recognizing thedisadvantages of previous gas-fired furnaces, provides a novel methodfor burning gaseous fuels with a broad base flame while developing afire very quickly. Furthermore, the burner of the present inventionprovides means for establishing a flame having a slow forward velocitywhile at the same time releasing its heat very quickly.

The present invention advantageously provides a straight-forwardarrangement for the preparation of a gas burner assembly.

The present invention further provides a novel gas burner assemblyincluding novel flame directing baffles for use in gas-fired furnaces.

Various other features of the present invention will become obvious tothose skilled in the art upon reading the disclosure set forthhereinafter.

More particularly, the present invention provides a gas burner assemblycomprising: a burner housing having fuel and air inlet means and anoutlet, the housing defining a plenum therein; a longitudinallyextending chamber of serrated configuration adapted to be receivedwithin the housing, the chamber having a plurality of generally V-shapedpockets therein, each pocket being defined by each serration, a gas ringmanifold adapted to be received within the housing, the manifold havingan inlet in communication with the fuel inlet means in the housing and aplurality of apertures spaced in axial alignment with the pockets of theserrated configured chamber whereby fuel enters the chamber through thepocket parallel to the axis of the chamber and, each V-Shaped pocketincludes two flanks, a first flank having at least one aperture thereinwhereby air entering the plenum through the air inlet in the housingpasses through the aperture in the flank transversely of the fuelpassing through the V-Shaped pocket and a second flank having a baffleattached thereto whereby fuel gas and air mixing in the pocket aredirected tangentially toward the center of the chamber.

It is to be understood that the description of the examples of thepresent invention given hereinafter are not by way of limitation.Various modifications within the scope of the present invention willoccur to those skilled in the art upon reading the disclosure set forthhereinafter.

Referring to the drawing:

FIG. 1 is a cross-sectional view of a gas-fired furnace of the presentinvention;

FIG. 2 is an enlarged exploded perspective view of a gas burner assemblyof FIG. 1 without a burner hous- FIG. 3 is another enlarged explodedperspective view of the gas burner assembly of FIG. 1 includingexpansion means with certain portions thereof cutaway;

FIG. 4 is an enlarged plan view of the expansion means of FIG. 1 withphantom lines indicating the position of the expansion means uponexpansion and contraction of the burner tube;

FIG. 5 is an enlarged perspective view of the front end of the gas-firedfurnace of FIG. 1; and,

FIG. 6 is an enlarged perspective view of the chamber of the gas burnerassembly of FIG. 1.

FIG. 1 illustrates a gas furnace 1 including a gas burner assembly 3 ofthe present invention. The gas furnace 1 includes a housing 2 having aninlet 4 for air which is to be heated in the furnace l and an outlet 6for the discharge of the heated air. Means for introducing air to beheated is not shown but may include any means known in the prior art,such as, for example, a blower.

The gas furnace l is further provided with a heat exchanger 7, the heatexchanger 7 including a plurality of elongated tubes 8 of relativelysmall cross-sectional area disposed about an enlarged cylinder or burnertube 9 of relatively large cross-sectional area with the tubes 8 beingaffixed at one end to a flue gas collector 11 and at the other end to arear tube sheet 12. The burner tube 9 is joined to the rear tube sheet12 at one end and a flexible expansion flange or head 19 at the otherend, the head 19 being attached to a corrugated collar 13, collar 13being connected to the front tube sheet 14 of the flue gas collector 11.The flexible expansion head 19 being disposed between the burner tube 9and the corrugated collar 13 is incorporated to relieve the expansionand contraction of the burner tube 9 as the temperature of the burnertube 9 fluctuates over a wide temperature range. It is realized that anexpansion means, such as flexible expansion head 19, may be adapted forpositioning between the burner tube and the rear tube sheet in additionto or in lieu of the aforementioned exemplified position of the flexibleexpansion head 19. The front tube sheet 14 of the collector 11 has anaperture 16 therein which is generally of the same diameter as thediameter of the corrugated collar 13 for axial alignment therewith.Further, burner assembly 3 is provided with an aperture 17 (FIG. 3) ofgenerally the same diameter as the corrugated collar 13 and the aperture17 is also adaptable for axial alignment with collar 13.

In FIGS. 2 and 3 the gas burner assembly 3 of the present inventionincludes housing 21 defining a combustion air plenum with combustion airinlet 22 and fuel gas inlet 23 disposed therein. The housing 21 isadapted to enclose a longitudinally extending cylindrical shaped chamber25 having a plurality of serrated sections 28 along the peripheralboundary of the chamber 25 and a fuel gas manifold distribution ring 24axially aligned with the chamber 25 The longitudinally extendingcylindrical shaped chamber 25 is determined by a flange or burnermounting plate 30 fixed at one end thereof and having an aperture 17therein and a front closure plate 26 fixed at the other end, plate 26having serrated edges for aligning with the serrated sections 28 of thechamber 25.

The serrated sections or interior pockets 28 of generally V-shapedcross-section are determined by a plurality of flanks 29 and 31, theflanks 31 having combustion air inlet apertures 27 disposed therein.Planks 29 (FIG. 6) include baffles 50 attached thereto, baffles 50 beingof V-shaped cross-section with the ends of each leg of the baffle 50being attached to a flank 29. Baffles 50 are provided to direct thecombustion air and the fuel gas, discussed hereinafter, and theresulting combustion products tangentially toward the center of thechamber 25. The front plate 26 is provided with a plurality of apertures42 therein along the serrated edges for communication with the interiorpockets 28, apertures 42 serving to permit the introduction of fuel gasinto the pockets 28 of the chamber 25. Apertures 42 are disposed toalign adjacent to the baffles 50 but interiorly thereof wherebycombustion air entering the pockets 28 is directed inwardly to mix andreact with the fuel gas at a distance spaced from the outer periphery ofthe chamber 25. It has been found that utilization of baffles 50 todirect the flame inwardly extends the life of the materials ofconstruction of the burner 3 by keeping the flame away from the burnerwalls and interiorly thereof.

In operation, fuel gas passes through apertures 42 from the fuel gasdistribution ring 24 (in a manner described hereinafter) parallel to thelongitudinal axis of the chamber 25 into individual pockets 28interiorly of baffles 50 of the chamber 25 and combustion air entersinto pockets 28 transversely of the fuel gas through apertures 27 inflanks 31 to develop a flame in the pockets 28. There are generally aplurality of apertures 27 for each flank 31 for uniform distributing ofcombustion air throughout the pockets 28. Front plate 26 is furtherprovided with a plurality of auxiliary combustion air inlets 43 in theform of radially extending slots and aconduit 44 for receiving a pilotgas assembly (not shown), the pilot gas assembly being constructed byany conventional method. The auxiliary air inlets 43 are spacedinteriorly of the apertures 42 providing additional combustion airparallel to the longitudinal axis of chamber 25, the additionalcombustion air being available as the flame being developed in theserrated pockets 28 moves tangentially toward the center of the chamber25.

The fuel gas manifold distribution ring 24 includes a fuel gas inletconduit 23 and a plurality of fuel gas outlets 33, the fuel gas outlets33 adapted to be aligned with selected fuel gas inlets 42 of the frontplate 26. FIGS. 2 and 3 illustrate that each pocket 28 is in alignmentwith a fuel gas outlet 33, but it is realized that it is not necessaryto introduce fuel to every pocket 28. For example, in operationsrequiring a relatively low BTU output of the burner, it may be desirableto utilize a distribution ring 24 having fuel gas outlets 33 for onlyonehalf of the pockets 28. Thus, gas outlets 33 would be aligned withalternating or every other pocket 28. Flange 32 including the fuel gasoutlets 33 is adapted for communication with the outer periphery of thefront closure plate 26 is affixed to the plate26 by any known method,such as bolting, welding, and the like.

In assembling the gas burner assembly 3 to the corrugated collar 13, aflange 18 is provided on the inlet to the corrugated collar 13 withapertures 38 therein. Front tube sheet 14 includes apertures 34 thereinfor alignment with apertures 38 of the collar 13 and apertures 37 inthe. burner mounting plate 30 of the gas as-v sembly 3; apertures 37,34, and 38 being in axial alignment to receive bolts 36 therethrough,bolts 36 being inserted through apertures 38, 34, and 37 with washers 39and nuts 41 being inserted thereon for holding gas assembly 3 in fluidtight communication with the corrugated collar 13 with the front tubesheet 14 being disposed therebetween. Burner housing 21 encircling thegas burner assemble 3 is then affixed to the front tube sheet 14 bymeans not shown, such as, welding, bolting, and the like.

FIG. 4 illustrates the operation of the annular flexible head 19surrounding burner tube 9 and fixed along its inner circumferencethereto when the burner tube 9 expands and contracts during-heat up andcool down of the furnace. Phantom lines illustrate that as the tube 9expands and contracts the corrugated collar 13 remains intact, annularflexible head 19 changing its position with movement of the burner tube9. The collar 13 in the example is of corrugated configuration toimprove the strength at the juncture of the burner tube 9 and the fluegas collector 11. It is realized that the corrugated collar 13 may bedesigned with deeper corrugations to allow for expansion andcontraction, thereby relieving stresses in the furnace, alleviating theneed for the flexing head 19. However, if the inside diameter of thecollar 13 is relatively small in relation to the outside diameter of thetube 9, a thin gauge stainless steel material may be used as the flexhead 19 to give sufficient flexibility for relieving stresses caused bythe expansion and contraction of the tube 9. For example, it has beenfound that for a collar 13 of 8 inches ID and a burner tube of 16 inchesOD, a flex head 19 of 20 gauge 316 type stainless steel is sufficientfor most applications.

FlG. 5 illustrates in detail the front end of the exemplified gas-firedfurnace of the present invention showing the flow of air across the unitto best utilize the heat transfer surfaceof the heat exchanger. Aspointed out previously, return tubes 8 are attached to the front tubesheet 14, lower return tubes 8a being disposed beneath the burnerhousing 21 and the upper return tubes 8b being disposed above the burnerhousing 21. The flue gas collector 11 is illustrated as a plenum ofgenerally C-shaped cross-section whereby the flue gas return from thelower return tubes 8a being collected in the lower portion of thecollector 1 1 passes upwardly along the side of the housing 21 beforemixing with the flue gas from the upper return tubes 8b.

It is noted that by allowing the hot flue gases to pass upwards alongthe side of the housing 21 it is advantageous for good heat transfer tointroduce the air to be heated in the heat exchanger at a point so thatit will contact the upwardly extending heat surface 45, surface 45 beingdisposed between the upwardly movin g hot flue gases and the generallyhorizontally moving relatively cold air.

The front end of the gas'fired furnace is further provided with aZ-shaped configured partition 46 as one side of the housing 21separating the combustion air plenum 5 (FIG. 3) from the flue gascollector 11. The Z-shaped partition 46 is attached at one end to thewall 47 of housing 21 and the front tube sheet 14 at the other. Thepartition 46 is of Z-shaped configuration to allow movement of the tubesheet 14 upon expansion and contraction of return tubes 8 during heat upand cool down of the furnace.

In the operation of the gas-fired furnace l of the present invention,pilot fuel gas and pilot combustion air are brought into the gas burnerassembly 3 through conduit 44 wherein the pilot gas mixture is ignitedby means not shown, such as, for example, electrode means, these meansof ignition of a pilot gas-air mixture being any known in the prior art.Combustion air is introduced into the assembly 3 from combustion airblower 40 (FIG. 5) through inlet 22 in housing 21 and apertures 27 inthe cylindrical shaped chamber 25, the air being directed transverselyto the flow of fuel in the pockets 28 of the chamber 25, the fuel gasbeing brought in through the ring 24 by way of fuel gas conduit 23 andin turn passes through the ring 24 and out by way of the apertures 33which are in alignment with the apertures 42 in the cylindrical shapedchamber 25. The pilot gas-air mixture ignites the fuel gas-air mixturein the pockets 28, the gas flame being developed in the pockets havingtangential direction toward the center of the chamber 25. Further,additional combustion air is fed interiorally of the chamber 25 throughradially slotted apertures 43 for further mixing and ignition of thefuel gas. Ignition of the fuel gas-air mixture in pockets 28 firstlyenables the firing of a mixture rich in fuel gas at these locationsthereby providing smooth and safe light offs while the gas flame beingdeveloped has tangential direction toward the center of the chamber 25.The gas flame developed in this manner has a broad base and a very slowforward velocity and when entering the burner tube 9 allows for almostmaximum heat release early in the cylinder or heat exchanger. It isfurther realized that because of the initial firing of a gas-air mixturerich in fuel gas the burner assembly 3 of the present invention does notrequire a gas-air premix before the gas is discharged into theindividual gas burning pockets 28 so the burner can use raw gas forcombustion purposes. The combustion gases upon leaving the burnerassembly 3 flow through the corrugated collar 13 and into the burnertube 9,

rear tube sheet 12, plenum l5, and then to the flue gas collector collar1 l by way of the elongated tubes 8. The combustion gases leave thefurnace through flue gas outlet 10 in the flue gas collector collar 11.

The air to be processed or heated by the heat exchanger enters thefurnace 1 through inlet 4 being moved therethrough by means not shown,such as a blower, circulating through the housing 2 in heat transferrelationship with he heat exchanger 7. The

heated air then leaves the furnace through the housing air outlet 6.

It is realized that various changes may be made to the specificembodiment shown and described without departing from the scope andspirit of the present invention.

What is claimed is:

l. A gas burner assembly comprising a burner housing, fuel and air inletmeans, and an outlet, said housing defining a plenum therein, a chamberof serrated crosssection configuration adapted to be received withinsaid housing, said chamber having a plurality of generally V-shapedpockets therein, each pocket being defined by each serration, a gas ringmanifold adapted to be received within said housing, said manifoldhaving an inlet in communication with said fuel inlet means in saidhousing and a plurality of apertures spaced in axial alignment with saidpockets of said serratedconfigured chamber whereby fuel enters saidchamber through said pockets parallel to the axis of said chamber; and,each V-shaped pocket includes two flanks, a first flank having at leastone aperture therein whereby air entering said plenum through said airinlet in said housing passes through said aperture in said flanktransversely of said fuel passing through said V- shaped pocket and asecond flank having a baffle attached thereto whereby fuel gas and airmixing in said pockets are directed tangentially toward the center ofsaid chamber.

2. In a gas-fired furnace including a heat exchanger and a gas-firedburner assembly, said gas-fired burner assembly having a central openingtherein in communication with said heat exchanger, said gas burnerassembly comprising a burner housing, fuel and air inlet means, and anoutlet, said housing defining a plenum therein; a chamber of serratedcross-section configuration adapted to be received within said housing,said chamber having a plurality of generally V-shaped pockets therein,each pocket being defined by each serration; a gas ring manifold adaptedto be received within said housing, said manifold having an inlet incommunication with said fuel inlet means in said housing and a pluralityof apertures spaced in axial alignment with said pockets of saidserrated configured chamber whereby fuel enters said chamber throughsaid pockets parallel to the axis of said chamber, and, each V-shapedpocket includes two flanks, a first'flank having at least one aperturetherein whereby air entering said plenum through said air inlet in saidhousing passes through said aperture in said flank transversely of saidfuel passing through said V-shaped pocket and a second flank having abaffle attached thereto whereby the fuel gas and the air mixing in thepockets are directed tangentially toward the center of said chamber.

I! t t =l=

1. A gas burner assembly comprising a burner housing, fuel and air inletmeans, and an outlet, said housing defining a plenum therein, a chamberof serrated cross-section configuration adapted to be received withinsaid housing, said chamber having a plurality of generally V-shapedpockets therein, each pocket being defined by each serration, a gas ringmanifold adapted to be received within said housing, said manifoldhaving an inlet in communication with said fuel inlet means in saidhousing and a plurality of apertures spaced in axial alignment with saidpockets of said serrated configured chamber whereby fuel enters saidchamber through said pockets parallel to the axis of said chamber; and,each V-shaped pocket includes two flanks, a first flank having at leastone aperture therein whereby air entering said plenum through said airinlet in said housing passes through said aperture in said flanktransversely of said fuel passing through said V-shaped pocket and asecond flank having a baffle attached thereto whereby fuel gas and airmixing in said pockets are directed tangentially toward the center ofsaid chamber.
 2. In a gas-fired furnace including a heat exchanger and agas-fired burner assembly, said gas-fired burner assembly having acentral opening therein in communication with said heat exchanger, saidgas burner assembly comprising a burner housing, fuel and air inletmeans, and an outlet, said housing defining a plenum therein; a chamberof serrated cross-section configUration adapted to be received withinsaid housing, said chamber having a plurality of generally V-shapedpockets therein, each pocket being defined by each serration; a gas ringmanifold adapted to be received within said housing, said manifoldhaving an inlet in communication with said fuel inlet means in saidhousing and a plurality of apertures spaced in axial alignment with saidpockets of said serrated configured chamber whereby fuel enters saidchamber through said pockets parallel to the axis of said chamber, and,each V-shaped pocket includes two flanks, a first flank having at leastone aperture therein whereby air entering said plenum through said airinlet in said housing passes through said aperture in said flanktransversely of said fuel passing through said V-shaped pocket and asecond flank having a baffle attached thereto whereby the fuel gas andthe air mixing in the pockets are directed tangentially toward thecenter of said chamber.